Commit dd78fedd authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

rmap: support file thp

Naive approach: on mapping/unmapping the page as compound we update
->_mapcount on each 4k page.  That's not efficient, but it's not obvious
how we can optimize this.  We can look into optimization later.

PG_double_map optimization doesn't work for file pages since lifecycle
of file pages is different comparing to anon pages: file page can be
mapped again at any time.

Link: http://lkml.kernel.org/r/1466021202-61880-11-git-send-email-kirill.shutemov@linux.intel.com

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7267ec00
......@@ -165,7 +165,7 @@ void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long, int);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long, bool);
void page_add_file_rmap(struct page *);
void page_add_file_rmap(struct page *, bool);
void page_remove_rmap(struct page *, bool);
void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
......
......@@ -3301,18 +3301,22 @@ static void __split_huge_page(struct page *page, struct list_head *list)
int total_mapcount(struct page *page)
{
int i, ret;
int i, compound, ret;
VM_BUG_ON_PAGE(PageTail(page), page);
if (likely(!PageCompound(page)))
return atomic_read(&page->_mapcount) + 1;
ret = compound_mapcount(page);
compound = compound_mapcount(page);
if (PageHuge(page))
return ret;
return compound;
ret = compound;
for (i = 0; i < HPAGE_PMD_NR; i++)
ret += atomic_read(&page[i]._mapcount) + 1;
/* File pages has compound_mapcount included in _mapcount */
if (!PageAnon(page))
return ret - compound * HPAGE_PMD_NR;
if (PageDoubleMap(page))
ret -= HPAGE_PMD_NR;
return ret;
......
......@@ -1494,7 +1494,7 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
/* Ok, finally just insert the thing.. */
get_page(page);
inc_mm_counter_fast(mm, mm_counter_file(page));
page_add_file_rmap(page);
page_add_file_rmap(page, false);
set_pte_at(mm, addr, pte, mk_pte(page, prot));
retval = 0;
......@@ -2962,7 +2962,7 @@ int alloc_set_pte(struct fault_env *fe, struct mem_cgroup *memcg,
lru_cache_add_active_or_unevictable(page, vma);
} else {
inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
page_add_file_rmap(page);
page_add_file_rmap(page, false);
}
set_pte_at(vma->vm_mm, fe->address, fe->pte, entry);
......
......@@ -259,7 +259,7 @@ static int remove_migration_pte(struct page *new, struct vm_area_struct *vma,
} else if (PageAnon(new))
page_add_anon_rmap(new, vma, addr, false);
else
page_add_file_rmap(new);
page_add_file_rmap(new, false);
if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new))
mlock_vma_page(new);
......
......@@ -1270,18 +1270,34 @@ void page_add_new_anon_rmap(struct page *page,
*
* The caller needs to hold the pte lock.
*/
void page_add_file_rmap(struct page *page)
void page_add_file_rmap(struct page *page, bool compound)
{
int i, nr = 1;
VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
lock_page_memcg(page);
if (atomic_inc_and_test(&page->_mapcount)) {
__inc_zone_page_state(page, NR_FILE_MAPPED);
mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
if (compound && PageTransHuge(page)) {
for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
if (atomic_inc_and_test(&page[i]._mapcount))
nr++;
}
if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
goto out;
} else {
if (!atomic_inc_and_test(&page->_mapcount))
goto out;
}
__mod_zone_page_state(page_zone(page), NR_FILE_MAPPED, nr);
mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
out:
unlock_page_memcg(page);
}
static void page_remove_file_rmap(struct page *page)
static void page_remove_file_rmap(struct page *page, bool compound)
{
int i, nr = 1;
VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
lock_page_memcg(page);
/* Hugepages are not counted in NR_FILE_MAPPED for now. */
......@@ -1292,15 +1308,24 @@ static void page_remove_file_rmap(struct page *page)
}
/* page still mapped by someone else? */
if (!atomic_add_negative(-1, &page->_mapcount))
goto out;
if (compound && PageTransHuge(page)) {
for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
if (atomic_add_negative(-1, &page[i]._mapcount))
nr++;
}
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
goto out;
} else {
if (!atomic_add_negative(-1, &page->_mapcount))
goto out;
}
/*
* We use the irq-unsafe __{inc|mod}_zone_page_stat because
* these counters are not modified in interrupt context, and
* pte lock(a spinlock) is held, which implies preemption disabled.
*/
__dec_zone_page_state(page, NR_FILE_MAPPED);
__mod_zone_page_state(page_zone(page), NR_FILE_MAPPED, -nr);
mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
if (unlikely(PageMlocked(page)))
......@@ -1356,11 +1381,8 @@ static void page_remove_anon_compound_rmap(struct page *page)
*/
void page_remove_rmap(struct page *page, bool compound)
{
if (!PageAnon(page)) {
VM_BUG_ON_PAGE(compound && !PageHuge(page), page);
page_remove_file_rmap(page);
return;
}
if (!PageAnon(page))
return page_remove_file_rmap(page, compound);
if (compound)
return page_remove_anon_compound_rmap(page);
......
......@@ -412,6 +412,12 @@ int __page_mapcount(struct page *page)
int ret;
ret = atomic_read(&page->_mapcount) + 1;
/*
* For file THP page->_mapcount contains total number of mapping
* of the page: no need to look into compound_mapcount.
*/
if (!PageAnon(page) && !PageHuge(page))
return ret;
page = compound_head(page);
ret += atomic_read(compound_mapcount_ptr(page)) + 1;
if (PageDoubleMap(page))
......
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